A well generally includes a wellbore (or “borehole”) that is drilled into the earth to provide access to a geographic formation below the earth's surface (or “subsurface formation”). The well may facilitate the extraction of natural resources, such as hydrocarbons and water from the subsurface formation, facilitate the injection of fluids into the subsurface formation, or facilitate the evaluation and monitoring of the subsurface formation. In the petroleum industry, hydrocarbon wells are often drilled to extract (or “produce”) hydrocarbons, such as oil and gas, from subsurface formations. The term “oil well” is often used to refer to a well designed to produce oil. In the case of an oil well, some natural gas is typically produced along with oil. A well producing both oil and natural gas is sometimes referred to as an “oil and gas well” or “oil well.”
Creating an oil well typically involves several stages, including a drilling stage, a completion stage and a production stage. The drilling stage normally involves drilling a wellbore into a subsurface formation that is expected to contain a concentration of hydrocarbons that can be produced. The portion of the subsurface formation expected to contain hydrocarbons is often referred to as a “hydrocarbon reservoir” or “reservoir.” The drilling process is normally facilitated by a drilling rig that sits at the earth's surface. The drilling rig can provide for operating a drill bit to cut the wellbore, hoisting, lowering and turning drill pipe and tools, circulating drilling fluids in the wellbore, and generally controlling various operations in the wellbore (often referred to as “down-hole” operations). The completion stage involves making the well ready to produce hydrocarbons. In some instances, the completion stage includes installing casing pipe into the wellbore, cementing the casing in place, perforating the casing pipe and cement, installing production tubing, installing downhole valves for regulating production flow, and pumping fluids into the well to fracture, clean or otherwise prepare the reservoir and well to produce hydrocarbons. The production stage involves producing hydrocarbons from the reservoir by way of the well. During the production stage, the drilling rig is normally removed and replaced with a collection of valves at the surface (often referred to as “surface valves” or a “production tree”), and valves are installed into the wellbore (often referred to as “downhole valves”). These surface and downhole valves can be operated to regulate pressure in the wellbore, to control production flow from the wellbore and to provide access to the wellbore in the event further completion work is needed. A pump jack or other mechanism can provide lift that assists in extracting hydrocarbons from the reservoir, especially in instances where the pressure in the well is so low that the hydrocarbons do not flow freely to the surface. Flow from an outlet valve of the production tree is normally connected to a distribution network of midstream facilities, such as tanks, pipelines and transport vehicles, which transport the production to downstream facilities, such as refineries and export terminals.
Although it is generally desirable to produce only hydrocarbons, such as oil, the production fluids often include other substances, such as water or gas. For example, if a reservoir contains pockets of water, the water may migrate to the wellbore, resulting in unwanted water production. The encroachment of a substance, such as water or gas, into a wellbore is often referred to as “breakthrough” of the substance (e.g., “water breakthrough” or “gas breakthrough”). The amount of water comingled with production may be characterized by a “water-cut” of the production. Oil production having a relatively large amount of water comingled therein will have a relatively high water-cut value, whereas oil production having a relatively small amount of water comingled therein will have a relatively low water-cut value. The amount of gas comingled with oil production may be characterized by a “gas-oil ratio” (or “GOR”) of the production. Oil production having a relatively large amount of gas comingled therein will have a relatively high gas-oil ratio, whereas oil production having a relatively small amount of gas comingled therein will have a relatively low gas-oil ratio.